I'd second this - or get a Lenovo Y500. Most of the systems they sell at Costco are trash with slow hard drives and poor quality GPUs.But no it will not affect your processing speed, but it WILL improve your Frames per second! My suggestion is, if you want to game, splurge $100 and get the dedicated GPU, since that will make a huge difference when gaming!
You can get the clevo Sager NP6350 for $900 with the 660m http/www.xoticpc.com/sager-np6350-clevo-w350etq-p-489... if the $100 is out of reach.